It is known to use artificial structures to assist muscular contraction. Such structures are adapted to assist atrial or ventricular contraction, or to assist or replace a natural sphincter. The use of such artificial sphincters has increased in recent years because faecal and urinary incontinences now affects more than 10% of people over 60 years of age and dramatically increases in patients over 80 years of age. Several pharmaceutical or surgical solutions have been developed for treating urinary and faecal incontinences. Generally, the outcome of surgery for treatment of urinary and faecal incontinence has to be regarded as low. The impacts on health care costs and overall quality of life of the patient are enormous.
The AMS800 artificial sphincter for urinary incontinence is commercialized by American Medical Systems and is composed of three components, a cuff, a pump, and a pressure-regulating balloon. The cuff is implanted at the bulbous urethra in males and is inflatable by means of a fluid. The pump is implanted in the scrotum and the pressure-regulating balloon is implanted in the abdomen. The major problems when using AMS800 is the tissue erosion around the urethra due to the constant pressure, the atrophy and irritation of tissues at the location of the inflatable cuff, and the emergency surgery for repair should the device remain in closed position in the event of mechanical failure. All other commercialized artificial sphincters whether for urinary or faecal incontinence bear similar drawbacks.
The ProAct™ artificial sphincter for urinary incontinence is commercialized by Uromedica and is composed of two small implantable balloons. During a short outpatient procedure, the balloons are surgically placed under the skin in the area where the prostate of the patient was surgically treated. The balloons help protect against accidental leaking of urine by increasing the amount of pressure required to urinate. When the patient needs to urinate, a normal amount of effort still should be required to push the urine out. However, the pressure from the balloons will help guard against unintentional urine loss, such as during a sneeze or cough. The major problems when using ProACT™ are identical to the problems using AMS800 artificial sphincter described above.
FlowSecure™, manufactured by Sterilin Ltd, another silicone hydraulic urinary sphincter similar to AMS800, has an extra pressure transmission balloon to transfer increased intra abdominal pressure directly to the cuff. Implantation of this device is technically feasible, but still difficult and is reported to be safe and effective in the short-term for the treatment of male urodynamic stress urinary incontinence, arising from a number of etiologies. However, the major problems when using FlowSecuren™ are identical to the problems using AMS800 artificial sphincter described above.
Some publications describe the use of artificial sphincters comprising shape memory alloy elements suitable for opening and closing a part of an organ in a living body. EP 1 238 638 describes an artificial sphincter having an opening/closing portion for opening and closing, wherein said opening/closing portion has:                a pair of elongated shape memory alloy elements that change reversibly between opposite shapes upon changes in temperature, and        hinges that link said pair of shape memory alloy elements together in a cylindrical shape.        
Such artificial sphincter is placed around the intestine of a human or animal inside the body near to an intestinal opening so that the opening/closing portion constricts the intestine. When the shape memory alloy elements are heated, they change shape, so that the constricting force on the intestine is lost.
However, as the opening/closing portion is still constricting the same region of the intestine, there is likely damage to this part of the body, and more especially a risk of tissue erosion, atrophy and burns, due to the constant pressure and heating of the shape memory alloy elements.
Reversible thermal lesions occur when the local temperature is increased to the 42° C. to 44° C. range (5 C-7° C. over the normal body temperature of 37° C.) and that irreversible thermal lesions occur when the local temperature is increased above 45° C. (>8° C. temperature rise over 37° C., which is the normal temperature). The time over overheating also plays an important role.
Moreover, in normal state, the shape memory alloy elements are not heated and are each bent to constrict the intestine. That means that heating is necessary to open the artificial sphincter. If the heating means fail, the sphincter remains closed and cannot be opened, what may be leading to life threatening complications. An emergency surgery is then necessary to open the artificial sphincter and to solve the problem.
Another artificial sphincter has been proposed in JP 07-051304. This document describes a constrictor comprising two shape memory alloy elements with different shape memories, and covered by covering materials.
The first covering material is formed in a shape to close the urethra in the daytime, and the second covering material is formed in a shape to half close the urethra in the night. This sphincter allows changing the pressure to the urethra, in order to prevent the incontinence in life action in the daytime, and to avoid necrosis of the tissue by loosing the pressure to the urethra in the night. If the shape memory alloy is no more efficient or is broken, the whole sphincter should be moved and replaced.
However, the drawbacks of such artificial sphincters are that there is a risk of tissue erosion and consequential necrosis, due to the high constant pressure to the urethra during the day and that there is a risk of incontinence during the night.
Moreover, JP 07-051304 discloses an artificial sphincter in which the shape memory alloy elements are disconnected from each other. This embodiment does not allow optimal pressure control.
Moreover, this kind of shape memory alloy elements uses a lot of power. That means that the battery needs to be changed very often or alternatively very large batteries have to be used.
Other medical devices comprising contractile element are known.
WO 2009/004092 discloses an artificial structure comprising several contractile elements adapted to contract an organ. But the contractile elements are connected to a support which is not flexible, in such a way that the contractile elements are not flexible one with respect to the other.
WO 2009/0048399 discloses an apparatus for controlling a flow of sperms in an uterine tube, comprising an implantable flow influence device to be applied on at least one portion of the uterine tube. The constriction device may comprise a clamping element, two clamping elements radially movable, an elongated circular constriction member or elastic strings interconnecting two annular holders. But this document does not disclose any contractile elements designed to contracting at least two portions of an organ, connected to a support and flexible along the uterine tube one with respect to the other.
WO 2007/066344 discloses an implantable extra cardiac compression device for left ventricular assistance in severe heart failure. The device comprises metal flanges that are passively flexed at springed-hinges by a vertically moving metal cup. The vertical movements of the metal cup are achieved by means, such as a motor driven rack-and-pinion mechanism, or, a linear induction motor system. The flanges are connected to each other by a high-tensile, elastic polymer membrane. However, with such device, the flanges are all in the same position, activated or not. As the flanges are moved by the moving of the cup, one flange cannot be in an activated position while the other flanges are in the resting position. Furthermore, one flange, used alone, cannot contract the organ.
US 2005/148814 discloses a device for assisting a heart comprising a carrier having a plurality of mutually interconnected electrically operated actuators, designed to compress at least a portion of the heart. In such device, one actuator, used alone, is not able to contract the organ.
WO 2009/127427 discloses a pressure device designed to be placed outside the body, and comprising several pressure segments able to apply a pressure on the body. The device discloses in this document is not implantable for contracting an internal organ. Furthermore, the pressure segments are not able to contract the portion of organ in such a way that said portion is closed.
Therefore there are, at the present time, no adequate solutions, whether commercial or in the literature, for implanting device comprising an artificial contractile structure, particularly for the treatment of faecal or urinary, incontinence.